1. Field of the Invention
The present invention relates to a method of dyeing plastic lenses, in particular, spectacle lenses, and a dyeing system used in the dyeing method.
2. Description of Related Art
Heretofore, a dip dyeing method has been used in many cases to dye plastic lenses for spectacles. In this method, a dye solution is prepared by mixing dispersible dyes of three primary colors, i.e., red, blue, and yellow, and dispersing the mixture in water. The thus prepared dye solution is heated to about 90xc2x0 C. A plastic lens is dipped in the heated dye solution, so that the lens is dyed.
As an alternative to the above dip dyeing method, a vapor deposition dyeing method has been proposed. This vapor-deposition dyeing method is carried out by heating a sublimatable dye to sublimate, thereby dyeing a plastic lens which is being heated.
In the above vapor-deposition dyeing method, the dyeing of lenses is effected by heating the sublimatable dye. As a result, a problem such as the disposal of waste solution after the dyeing will not arise. However, such the method has disadvantages that it is difficult to deposit dyes at a fixed quantity to adhere on a lens surface, to prepare dyes in desired density, and to dye lenses in a deep color. The hue or tint of a dye to be used is almost artificially prepared. As a result, the prepared dye is apt to be uneven in color, which will cause a large problem in quality control.
The conventional dip dyeing method mentioned above has also disadvantages that the interaction and condensation of the dispersible dyes cause variations and unevenness of hue or tint. This disables the stable provision of uniformly dyed objects. In addition, the dye solution after used has to be discharged finally, which causes a problem of disposal of waste solution and also prevents the effective use of dyes. In the dip dyeing method, furthermore, since the dye solution is heated, the dyeing work is carried out in the high-temperature and humidity environment, in which the foul smelling resulting from the dye is also present. The use of the dip dyeing method thus causes a deteriorated working environment.
The present invention has been made in view of the above circumstances and has an object to overcome the above problems and to provide a dyeing method capable of facilitating preparation of dyes in desired density and also dyeing plastic lenses with a stable hue or tint in every dyeing works, and improving a working environment thereof, and a dyeing system to be used for achieving the dyeing method.
Additional objects and advantages of the invention will be set forth in part in the description which follows and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and attained by means of the instrumentalities and combinations particularly pointed out in the appended claims.
To achieve the purpose of the invention, there is provided a method of dyeing a plastic lens, including a first step of printing a print area on a print base body with a dyeing solvent by using a printer electrically controlled, the dyeing solvent containing a dissolved or fine-grained dispersed sublimatable dye, a second step of placing the print base body having the print area printed with the dyeing solvent in a position where the print area faces a plastic lens to be dyed without contact therewith, and a third step of heating the print base body in a vacuum to sublimate the dye and deposit the sublimated dye on the lens.
According to another aspect of the present invention, there is provided a system for dyeing a plastic lens, including a printer which is electrically controlled to print a print area on a print base body with a dyeing solvent containing a dissolved or fine-grained dispersed sublimatable dye, a deposition device for heating the base body in a vacuum to sublimate the dye and deposit the sublimated dye on the lens to be dyed, the lens being placed in a position where the lens faces the print area printed on the base body without contact therewith.
In the present invention, a print base body having a print area formed with the dyes which can be easily prepared in a desired density is used to dye plastic lenses, so that the plastic lenses can be dyed in a desired density and a stable hue. Since the dyeing operation is conducted in a dry environment, the dyeing working environment can be also improved as compared with a conventional wet environment.